Conventionally, as such a power output apparatus, there has been known a power output apparatus including an internal combustion engine, two motors, a so-called ravigneaux planetary gear mechanism, a parallel shaft-type transmission capable of selectively coupling two output elements of the planetary gear mechanism to an output shaft (for example, see Patent Document 1). The power output apparatus is adapted for a front-wheel-drive vehicle, and the power output apparatus is configured such that the internal combustion engine is arranged transversely, as well as the rotating shafts of the internal combustion engine and the planetary gear mechanism, the two motors, and the parallel shaft-type transmission extend in parallel to each other. In addition, conventionally, there has been known a power output apparatus including a planetary gear device having an input element connected to an internal combustion engine and two output elements; and a parallel shaft-type transmission having a countershaft connected to each of the corresponding output elements of the planetary gear device (for example, see Patent Document 2). According to the power output apparatus, each of the two output elements of the planetary gear device is fixed to an inner periphery of a corresponding rotor in an electric drive section.    Patent Document 1: Japanese Patent Laid-Open No. 2005-155891    Patent Document 2: Japanese Patent Laid-Open No. 2003-106389